1. Field of the Invention
This invention is useful for asymmetric synthesis of various natural products and medicines. More particularly, it relates to arylacetic acid esters useful in preparing optically active prostaglandins and process for the production the said esters.
2. Description of the Prior Art
As to methods for preparing such optically active compounds, Diels-Alder reaction, enzymatic hydrolysis of the diester moiety, or the like is well known. However, such products as prepared by those reactions have generally low optical purity or, even if the optical purity would be high, impurities such as enantiomers are hardly removed. Furthermore, in the aforesaid enzymatic hydrolysis, there are difficulties with the acceptability of the reactant with enzymes or in setting reaction conditions for the enzymes. Therefore, it has been quite difficult to obtain optically pure compounds, economically on a large scale.
It is significant to obtain compounds in a high optical purity by asymmetric synthesis without using an enzyme in synthesis of natural organic compounds as well as in synthesis of various other compounds including medicines in a broad sense.
This invention is intended to provide the optically active intermediates which are useful for the asymmetric syntheses for various optically active compounds, especially medicines in a high purity. This invention also provides processes for preparing optically pure intermediates by promoting the reaction stereoselectively and removing with ease small quantities of by-products resulting in the course of the reaction. This invention is further intended to make it possible to carry out the said reaction easily with inexpensive reagents.